In a SAW filter, an electrical signal is converted into an acoustic wave and vice versa. In the propagation of the acoustic wave in a SAW transducer, diffraction losses arise in the peripheral area of the transducer due to the radiation of part of the surface waves in the transversal direction. A method for suppressing higher transversal modes or for adapting the excitation profile of a transducer to the form of the fundamental transversal mode is known, for instance, from the publication DE 196 38 398 C2.
Additional SAW transducers that have regions in the transversal direction with mutually differing velocities of the acoustic wave are known from the publications DE 10331323 A, EP 1,471,638 A2 and U.S. Pat. No. 6,121,860.